All eyes on roaring McIlroy

The PGA Championship in Louisville, Kentucky is likely to deliver further confirmation that a new world order is establishing itself in the game with players such as Rory McIlroy and Adam Scott now leading the way.

While Tiger Woods, Phil Mickelson, Ernie Els and Vijay Singh have been golf's dominant figures over the past two decades, the present and immediate future appears to belong to McIlroy, Scott, Bubba Watson, Martin Kaymer and other 'young guns'.

Masters champion Watson and US Open winner Kaymer have each won two majors while in-form McIlroy, who clinched his third at the British Open last month in wire-to-wire fashion, will be aiming for a career Grand Slam at next year's Masters.

Australian world number two Scott landed his first major championship crown at the 2013 Masters and ever since has been a perennial contender in golf's blue riband events.

The PGA Championship has often been the most unpredictable of the four majors, in part because it attracts the strongest field, and this week is no different with 99 of the world's top 100 players entered to compete at Valhalla.

Long-hitting American Dustin Johnson will not be there while he takes an indefinite leave of absence from golf to seek help for "personal challenges" and there is also some doubt over the participation of former world number one Woods.

Four-time PGA champion Woods, who had surgery in late March to treat a pinched nerve in his back, pulled out of the WGC-Bridgestone Invitational on Sunday following a back spasm and is expected to make a very late decision over his participation.

With or without Woods, a host of contenders will be competing for "glory's last shot" in the season's final major.

There is a chance of thunderstorms in Louisville on Thursday and Scott believes a rain-softened Valhalla layout, with more receptive greens, will lengthen the list of potential winners.

Newly crowned world number one McIlroy, who romped to victory by a record eight shots in the 2012 PGA Championship at Kiawah Island, heads to Valhalla with his game in sparkling form.

He became the third youngest player in the modern era, after Jack Nicklaus and Woods, to win three of the four majors with his triumph in last month's British Open at Hoylake, then won the Bridgestone Invitational on Sunday in his next start.

Other likely contenders include 2010 champion Kaymer of Germany, Spanish world number three Sergio Garcia, fourth-ranked Swede Henrik Stenson and last year's US Open winner Justin Rose of England.